Enhanced features for backflow prevention device enclosure

ABSTRACT

An apparatus for maintaining the temperature of material conveyed through fluid conveying devices. The apparatus may include an enclosure having an improved door, mounting bracket, locking mechanism, heating device and a secure structure for accessing the upper portion of the enclosure. An alignment guide and integral tabs are also disclosed which facilitate assembly of the enclosure. The apparatus may include an enclosure supported upon a chase or chases, which may extend from the enclosure downwardly to the frost line. Heating elements may be included within the chase(s) or enclosure to maintain the temperature of the material and the fluid conveying devices surrounding the material above a predetermined setpoint all the way to the frost line. The enclosure may employ a suitable valve to facilitate the removal of discharged material from the enclosure in applications where the fluid conveying device discharges material to the atmosphere.

RELATED APPLICATIONS

[0001] This application is a continuation of U.S. patent application Ser. No. 09/456,257, filed Dec. 7, 1999, now ______, which is a continuation of U.S. patent application Ser. No. 08/820,196, filed Mar. 19, 1997, now U.S. Pat. No. 5,996,611, which is a continuation-in-part of U.S. patent application Ser. No. 08/743,939, filed Nov. 5, 1996, now U.S. Pat. No. 5,740,832 and is a continuation-in-part of U.S. patent application Ser. No. 08/743,940, filed Nov. 5, 1996, now U.S. Pat. No. 5,743,289, the disclosures of which are incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

[0002] The invention relates in general to an apparatus for protecting fluid conveying devices from freezing. More particularly, the invention relates to a drain door for facilitating the removal of discharged fluid from an apparatus that protects backflow prevention devices and their associated piping. The invention also relates to an improved locking mechanism, heater and a variety of structural enhancements that aide in the construction and installation of the apparatus of the invention. Additionally, the invention relates to an elevated, insulated enclosure for protecting a backflow prevention device and its associated piping above ground and below the surface of the ground to the frost line.

[0003] Backflow prevention devices are well known and typically include an assembly of one or more check valves installed in a pipeline. These devices prevent the reverse flow, or backflow, of fluid from the downstream pipeline to the upstream supply pipeline or main, which can result when the fluid pressure in the upstream supply pipeline falls below the fluid pressure in the downstream pipeline. The prevention of backflow is particularly important when the downstream pipeline contains contaminated material and the upstream supply pipeline is carrying potable water.

[0004] Backflow prevention devices may or may not discharge fluid to the atmosphere. For example, a double check assembly does not discharge fluid. However, when the prevention of backflow is necessitated by health considerations, such as in an installation where contaminated water could be conveyed back into a potable water main, a reduced pressure zone device is included in the assembly. Reduced pressure zone devices discharge a large volume of water when actuated, and thus the downstream water, which may be contaminated, is transferred out of the downstream pipeline to the atmosphere and not back into the upstream supply pipeline. Besides discharging large volumes, these reduced pressure zone devices intermittently discharge small quantities of water. Since these backflow prevention devices are frequently installed in a water supply line outdoors and above ground, it is important that the devices be enclosed and protected from the weather, and particularly from freezing.

[0005] It is well known that water lines need to be protected from freezing. Many pipelines are run underground to avoid exposure to ambient temperatures that are below the freezing point of water. Pipelines are also run underground for aesthetic reasons. While a majority of a pipeline may be underground, backflow prevention devices and their associated valving and piping cannot be buried underground because access is needed for proper operation and maintenance of the backflow prevention device. Additionally, discharging backflow prevention devices must be elevated because they must not be submerged in the discharged material. Therefore reduced pressure zone devices cannot be buried in the ground or installed in a floodable pit for the additional reason that they must not be submerged. Thus, in many installations the pipeline is run underground and the portions of the pipeline having backflow prevention devices are constructed above ground level. The backflow prevention devices, valves, and portions of the pipeline are subject to freezing and may become inoperable unless they are protected from the weather.

[0006] Years ago, large concrete or cast iron boxes were constructed around backflow prevention devices. A door was provided in the top of the box to provide access to the interior of the box for servicing the device. Open drain holes were formed in the lower portions of the walls of the box to drain any water discharged by the backflow prevention device away from the box. These boxes were inferior due to the material of construction and because access to the interior of the box was difficult. Moreover, due to the open fixed drain holes in these boxes, water, foreign objects and most importantly cold air would enter the interior portion of the box. The movement of cold air into the box defeated a central purpose of its design by facilitating the freezing of the water within the backflow prevention device and its associated piping and valving.

[0007] U.S. Pat. No. Re 33,523, to Devine, discloses another type of apparatus for protecting a backflow prevention device. This apparatus includes a sectionalized cover which is held together by clamps. The top portion of the cover has openings to permit manipulation of the protruding valve stems which extend above the cover. Drain openings are provided at ground level to permit drainage of liquid from the space within the cover. These drain openings are covered by a screen and vertically cut flaps which hang from the top of the opening to ground level. The cover is insulated and includes an electric heating element placed in the upper portion of the cover interior. Devine does not describe how his apparatus sections are aligned and mounted. Although there are many drawbacks associated with the Devine cover, the openings in the top portion and the flap-covered drain openings allow air to be transferred to and from the interior of the cover, thus significantly increasing the heating requirements of the cover and, in some cases, making freeze protection impractical. Further, the drain openings are not adequately sealed by the flaps and can be blocked by ice, snow, vegetation, dirt, debris, and other objects since the drain openings are at ground level. Additionally, heat may be transferred only in the area above the surface of the ground.

[0008] Another type of cover is disclosed in U.S. Pat. No. 4,890,638 (the “'638 patent”), which includes a cover member having a top, which is a unitary structure, and four walls. The '638 patent has drain openings at the bottom portion of its walls to allow water discharged by the backflow prevention device to escape from the interior of the cover. These drain openings are covered by drain doors, which are of the same rigid construction as the cover walls, are hingedly attached to the cover walls, and are spring biased to be maintained in a closed position. This cover reduces some of the flow of cold air to the backflow prevention device, however it suffers from the limitations that air can blow under the doors and the temperature of the portion of the pipeline above the frost line and below the ground cannot be controlled. Like the Devine apparatus, the drain openings in the '638 patent can be blocked by a variety of objects because they are also at ground level. Furthermore, the drain flap construction is such that a small object can block the entire drain opening. The '638 patent does not describe a heater or the alignment and mounting structures of the present invention. Additionally, this cover suffers from a variety of drawbacks including the fact that the spring abruptly snaps shut and must be maintained, because it breaks and becomes stretched out after a heavy discharge of fluid through the drain opening.

[0009] U.S. Pat. No. 5,609,784 describes an apparatus and method for covering and heating fluid flow devices, which adds a heater positioned on the ground surface in the interior of the cover described in the '638 patent.

[0010] The foregoing demonstrates that there is a need for an energy-efficient enclosure which protects backflow prevention devices and the portion of the connected pipeline above the frost line from freezing, improves drain door operation, avoids blockage of the drain openings, improves mounting and alignment of the enclosure, increases the efficiency of the heating operation, and facilitates inspection of the backflow prevention device.

SUMMARY OF THE INVENTION

[0011] The invention satisfies the need and avoids the drawbacks of the prior art by providing an apparatus which efficiently protects a backflow prevention device or any number of fluid conveying or monitoring devices from freezing to a depth to the frost line. The invention further prevents blockage of the drain openings by ice, snow, vegetation, dirt, debris, and other objects and avoids the potential of submerging the fluid conveying devices in discharged fluid.

[0012] More specifically, the invention provides an apparatus for maintaining the temperature of the material conveyed through a pipeline above the freezing point of the material. The apparatus of the invention may include an enclosure being supported upon a chase or chases, which extend from the enclosure to ground level or into the ground and downwardly to the frost line. Heating elements, which may be powered in any known manner, may be included within the chases or enclosure to maintain the temperature of the material and the fluid conveying devices. In one embodiment that may be employed in connection with backflow prevention devices that utilize reduced pressure zone devices, the enclosure may include a suitable valve adjacent an opening in its bottom wall, which is above ground level, to prevent cold air, ice, snow, animals, vegetation, trash, dirt and the like from entering the enclosure yet allowing for effective removal of discharged water from the enclosure.

[0013] Additionally, the invention provides an insulated enclosure having a self-closing, gravity-biased door that allows for full fluid flow, is maintenance free, tamper resistant, and easy to manufacture. Additionally the hinge employed in connection with this door is disposed on the inside of the enclosure making it less susceptible to vandalism and seizure due to snow and ice. The invention also discloses an improved mounting bracket having risers that extend outside of the enclosure and a rod which extends through openings in the enclosure and mounting bracket. The invention further discloses an improved, secure structure for accessing the upper portion of the enclosure. An alignment guide and integral tabs are also disclosed which facilitate assembly of the enclosure. The invention also describes various heating mechanisms and in one embodiment a sleeve is shown which extends into the slab, through the slab and even extends to the frost line.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a perspective view of an enclosure, shown partially in phantom, enclosing a backflow prevention device and its associated valving and upstream and downstream piping.

[0015]FIG. 1A is another perspective view of an enclosure which identifies a pair of drain doors.

[0016]FIG. 2A is a side view of an enclosure constructed according to the principles of the invention illustrating one embodiment of a drain door.

[0017]FIG. 2B is a top view of an enclosure taken along line 2B-2B in FIG. 2A.

[0018]FIG. 3A is a side view of another enclosure constructed according to the principles of the invention illustrating one embodiment of an enclosure roof.

[0019]FIG. 3B is a top view of an enclosure taken along line 3B-3B in FIG. 3A.

[0020]FIG. 4 is an enlarged end view of the drain door demonstrated in FIG. 2A taken along line 4-4.

[0021]FIG. 5 is a top view of the enclosure depicted in FIG. 3A.

[0022]FIGS. 6A and 6B are similar to FIGS. 3A and 5 showing the roof in a partially open position.

[0023]FIGS. 7, 8 and 9 illustrate various views of the roof of the enclosure constructed according to the principles of the invention.

[0024]FIGS. 10A and 10B demonstrate one manner of closing and latching, from the interior of the enclosure, the roof portion.

[0025]FIG. 11 provides a top view of the alignment guide constructed according to the principles of the invention.

[0026]FIGS. 11A, 11B and 11C are end views of the alignment guide depicted in FIG. 11 taken along lines 11A-11A, 11B-11B, 11C-11C, respectively.

[0027]FIGS. 12 and 13 are side views of the lower portion of an enclosure and the slab that the enclosure is resting upon.

[0028]FIGS. 12A and 13A are top views of FIGS. 12 and 13 taken along lines 12A-12A and 13A-13A, respectively.

[0029]FIG. 14 is a side view of an enclosure having a heating unit constructed according to the principles of the invention.

[0030]FIG. 15 is a side view of an enclosure having another heating unit constructed according to the principles of the invention.

[0031]FIG. 16 is a perspective view of an enclosure and locking mechanism constructed according to the principles of the invention.

[0032]FIG. 17 is a top view of an enclosure and locking mechanism as shown in FIG. 16 with the roof removed from the enclosure.

[0033]FIG. 17A is an end view of the enclosure shown in FIG. 17 taken along line 17A-17A and includes a locking rod.

[0034]FIG. 17B is an enlarged view of the locking mechanism shown in FIG. 17A.

[0035]FIG. 18 is a side view of the device illustrated in FIG. 17.

[0036]FIG. 19 is a side view of the device illustrated in FIG. 17B.

[0037]FIG. 20 is a side elevational view of an elevated cover enclosing a backflow prevention device including its associated valving and upstream and downstream piping, with the ground level frost line and concrete footers identified.

[0038]FIG. 21 is a side elevational view of an elevated cover constructed according to the principles of the invention with the heater element shown in phantom.

[0039]FIG. 21A is an enlarged view of the section 21A of FIG. 21 which illustrates the connection between the heater element and electrical cabinet.

[0040]FIG. 22 is a cross-sectional top view of the elevated cover taken along line 22-22 of FIG. 21.

[0041]FIG. 23 is an elevational view, partially in cross-section, of the elevated cover taken along line 23-23 of FIG. 21 with the heater element shown in phantom.

[0042]FIG. 23A is an enlarged view of section 23A of FIG. 23 which illustrates the connection between the top wall and side walls.

[0043]FIG. 24 is a perspective view of the structural supports utilized in one embodiment of the invention.

[0044]FIG. 25 is an end view of FIG. 24.

[0045]FIG. 26 is a cross-sectional side elevational view of a discharge valve of the elevated cover taken along line 26-26 of FIG. 22 and constructed according to the principles of the invention.

[0046]FIG. 27 is a cross-sectional end elevational view of the discharge valve shown in FIG. 26 taken along line 27-27 of FIG. 21.

[0047]FIGS. 28, 29 and 30 are end elevational views of the discharge valve shown in FIG. 26 illustrating the valve in closed, partially open and fully open positions, respectively.

[0048]FIG. 31 is a side elevational view of another discharge valve of the elevated cover constructed according to the principles of the invention.

[0049]FIG. 31A is an enlarged view of the discharge valve of FIG. 31.

[0050]FIG. 32 is an end elevational view of the discharge valve of FIG. 31.

DETAILED DESCRIPTION

[0051]FIG. 1 generally illustrates one embodiment of the invention. The enclosure 1, partially shown in phantom, encloses a backflow prevention device, which is depicted in FIG. 1 as two check valves C, a relief valve PR, servicing valves V and inlet and outlet piping P. Although the invention is described for use in connection with a backflow prevention device, the enclosure may be employed to maintain the temperature of material being conveyed through any number of fluid conveying or monitoring devices, such as meters, vacuum breakers, standpipes, pressure regulators, and pumps (referred to generally herein as “fluid conveying devices”). The invention is particularly useful for pipelines carrying water, however its principles may be used for the protection of fluid conveying devices transferring any other material where either the material itself or the fluid conveying device(s) surrounding the material is susceptible to solidification, such as a pressure regulator controlling the flow of natural gas.

[0052] The assembly shown in FIG. 1 constitutes a portion of a substantially longer pipeline wherein a majority of the pipeline is installed underground. The backflow prevention device is constructed above the ground to allow for its monitoring and servicing. Additionally, if the device is one that discharges water, enclosure 1 should be equipped with a door 6 and the backflow prevention device must be disposed high enough above ground level to permit the discharge of water to the atmosphere and out door 6 without submerging the backflow prevention device.

[0053] In this embodiment, enclosure 1 is depicted as a rectangular box that may be supported by concrete slab 19. Enclosure 1 may be bolted to concrete slab 19 or attached in any suitable manner known in the art. Concrete slab 19 may go below or rest upon the surface of the ground or pavement and may also be supported upon other surfaces, such as the ground or a slab made of a material other than concrete. Slab 19 may be of various sizes depending on the size of the fluid conveying device and the enclosure 1. While the slab height 19 h may be any suitable distance, it may be several feet in some instances so that enclosure 1 may be protected from various dangers, such as automobiles that may drive into and damage enclosures (and fluid conveying devices) that are installed adjacent parking lots and roadways. The slab 19 may be pre-fabricated or it may be poured around piping P.

[0054] According to the principles of the invention, enclosure 1 may be of any construction. In one embodiment, enclosure 1 is made of a panel of rigid insulation covered by sheet metal. Enclosure 1 may include access doors to allow for service and monitoring of the fluid conveying devices similar to that described in U.S. Pat. Nos. Re 33,523, 4,890,638 and 5,609,784, the disclosures of which are incorporated by reference herein in their entirety. Access to the fluid conveying device(s) may be had by removing any of the panels such as center panel 1C, by removing the roof 40, by opening a portion of the roof 40B, by removing the entire enclosure (for smaller installations) and by various other mechanisms.

[0055]FIG. 1A demonstrates two alternative embodiments of the invention in a single drawing. Side drain door 6S provides one mechanism to allow discharged water to be removed from the enclosure and end drain door 6E provides another. While multiple doors may be employed on the sides or ends of the enclosure 1 in any combination, typically side drain doors 6S are used in enclosures 1 enclosing backflow prevention devices having diameters equal to or greater than three inches and end drain doors 6E are employed in smaller enclosures 1, which enclose devices that are smaller than three inches in diameter such as enclosure 1 illustrated in FIG. 16.

[0056]FIGS. 2A and 2B display side and top views, respectively, of an enclosure 1 having a door 6 located on one side of the enclosure 1. These Figures show door 6 as being insulated in a manner which is substantially similar to end panels 1E, side panels 1S and center panel 1C that define the enclosure 1. Door 6 is illustrated in its normally closed position, which is indicated as closed door 6A. In this embodiment, door 6 is attached to center panel 1C using a continuous hinge 7 or any other device which allows door 6 to be maintained in a normally closed position and permits the door to be opened when fluid needs to be discharged from inside the enclosure 1. A plurality of hinges may be substituted for continuous hinge 7 and the hinge or hinges may be made of any non-rusting material, although stainless steel and thermoplastic materials are preferred. Zees 5A and 5B are attached to the sides and inside flange of center panel 1C. The lower portion of the zees 5A and 5B space door 6 above slab 19 and permit door 6 to freely move outwardly away from the enclosure 1 to enclosure exterior 300 as is more clearly shown in FIG. 4 allowing fluid to be discharged from the enclosure interior 200. The inside portions of the zees 5A and 5B provide stops 5AI and 5BI for the door 6 such that door 6 cannot swing into the enclosure interior 200 due to the force of gravity.

[0057]FIG. 4 is an enlarged sectional view of FIG. 2A illustrating the details of the door of the invention. Door 6A is shown in the closed position against door stop 5AI and is attached to hinge 7. Hinge 7 may be secured to the inside portion of the center panel 1C which may be flush with door stop 5AI and 5BI. The orientation of the hinge 7 mounting relative to the door stops 5AI and 5BI is an important feature of the invention as the positioning of these structures allows the door 6 to be securely biased against the stops 5AI and 5BI by virtue of the effect of gravity. This is due to the fact that the door 6 is designed so that its centroid is located in the enclosure exterior 300 of the enclosure 1. Thus, due to gravity, the door 6 desires to swing inwardly toward the interior 200 of the enclosure. To the extent that the door 6 is securely biased against the stops 5AI and 5BI, the enclosure 1 is more tightly insulated and is therefore more energy efficient. When full flow occurs from the interior 200 of the enclosure to the exterior 300, door 6 pivots from its closed position 6A to a fully open position 6B shown in phantom. As is depicted in FIG. 4, if the insulating materials utilized in door 6 and center panel 1C are incompressible, door 6 may be fabricated with notched portion 6N to enable the door 6 to reach a fully open position 6B without being blocked by the lower portion of center panel 1C. While the notched portion 6N of the door 6 has some drawbacks due to the lack of insulating materials along this portion of the door 6, it has the advantage of allowing unobstructed fluid flow through the discharge opening and the assurance that the door is securely closed against the stops 5AI and 5BI when the flow has subsided. Of course, if compressible insulation is employed in the lower portion of center panel 1C and/or the upper portion of door 6, then the size of the notched portion 6N may be minimized or eliminated.

[0058]FIGS. 3A, 3B and 5 show another embodiment of the invention and are directed to alternative advantageous features which may be employed in a backflow prevention device enclosure 1. FIG. 3A shows an enclosure 1 which may be mounted on slab 19. The roof 40 of the enclosure 1 is depicted as being divided into two separate portions 40A and 40B which are attached together via a hinge 37. The roof 40 may be hinged in different places resulting in a variety of differently sized portions 40A and 40B. Access to differing parts of various backflow prevention devices and the overall weight of the roof 40 are factors considered in determining the number and size of the roof portions. FIGS. 6A and 6B are similar to FIGS. 3A and 5 with the exception that the roof 40 is shown in the open position. Notably, roof portion 40B is not propped in the air, but rests on roof poriton 40A which provides an important safety advantage. The roof design illustrated in FIGS. 3A, 3B, 5, 6A and 6B was developed specifically to enclose and protect the fluid conveying device where it was desirous to service the backflow prevention device from above without removing either the entire roof or a wall of the enclosure 1.

[0059]FIGS. 3A, 3B and 5 demonstrate structurally integrated mounting tabs 38A-D and 39A-D which may be employed to attach enclosure 1 to slab 19. In a preferred embodiment, these tabs 38A-D and 39A-D are integrally fabricated as part of enclosure 1 which provides added strength and eliminates the need for an installer to mate separate tabs to the enclosure 1 before affixing the enclosure to slab 19. FIGS. 12, 12A, 13 and 13A illustrate, in greater detail, structurally integrated mounting tabs 38A and 39A which are depicted as being integral with side panel 1S (partially shown). Screws 38S and 39S affix side panel 1S to slab 19 and pass through tabs 38A and 39A. When an installer has a panel in place, for example side panel 1S, the panel can be immediately attached to slab 19 without first having to find and attach a distinct tab to the enclosure 1. FIGS. 12A and 13A show top views of side panel 1S.

[0060]FIG. 3B depicts alignment guide 55 which is another feature of the invention. During assembly, the alignment guide 55 may be placed along one or both sides of enclosure 1 adjacent to side panels 1S and center panel 1C. The alignment guide 55 may be utilized to ensure that the center panel 1C and side panels 1S are properly aligned prior to attaching the enclosure 1 to slab 19. FIGS. 11, 11A, 11B and 11C provide further detail to the alignment guide 55. When the alignment guide 55 is in position, horizontal leg 55B will rest on slab 19. Vertical leg 55A may be held flush against side panels 1S so that the panels can be properly aligned. The second horizontal surface is identified as horizontal center leg 55C. Horizontal center leg 55C extends into the opening that exists between the side panels 1S and may be designed to be nominally the same width as center panel 1C, thus the side panels 1S are installed at a distance such that center panel 1C may be installed there between. The method for aligning the side panels 1S may be accomplished by first placing the alignment guide 55 on its horizontal leg 55B in the proper position on slab 19. Next, side panels 1S are placed against vertical leg 55A and horizontal center leg 55C as is generally shown in FIG. 3B. After the side panels 1S are properly aligned they are fixed to slab 19 and the alignment guide 55 may be discarded.

[0061]FIG. 7 illustrates the roof 40 in greater detail from one end of the enclosure 1. The outer portion of the roof 40 is shown locked to pocket channel 42 and the pocket channel 42 is shown locked to insulation retaining angle 43. A structural channel 56 is depicted traversing from one side of the enclosure 1 to the other and may be attached at either end to insulation retaining angles 43. The structural channel 56 may be employed to enhance the structural integrity of the enclosure 1 and to further strengthen the structure, particularly when the roof 40 of the enclosure 1 is not attached to the panels of the enclosure 1.

[0062]FIG. 8 is related to FIG. 7 and details the engagement of the roof 40 with a side panel 1S. As is shown in FIG. 7, roof 40 is locked to pocket channel 42 which is locked to insulation retaining angle 43. When the side panel 1S and roof 40 are in place a self tapping machine screw 49 or any other suitable attaching device may be inserted through hole 49A to fix the side panel 1S to the pocket channel 42 and insulation retaining angle 43. The roof 40 and side panel 1S include insulating panels 44/45 and 46, respectively.

[0063]FIG. 9 is a sectional view of FIG. 7 taken along line 9-9, which is similar to the upper portion of the side view shown in FIG. 3A. Roof portions 40A and 40B are shown in the closed position and are attached by hinge 37. Structural channel 56 is illustrated from one end inserted between the insulating panels 44 and 45. Pocket channel 42, insulation retaining angle 43 and holes 49A and 49B, described above, are also identified in FIG. 9.

[0064]FIGS. 10A and 10B illustrate further embodiments relating to an enclosure 1 having roof portions 40A and 40B as was generally shown in FIGS. 3A and 6A. In use, the enclosure depicted in FIGS. 3A and 6A would have the roof portion 40B in the closed position and engaged with vertical insulation retainer 53. Vertical insulation retainer 53 has two bent sides 53R which stiffen and strengthen the retainer 53 and hold insulating panel 51 of end panel 1E in place. Insulating panel 51 is shown having an exposed reflective surface 33. For security purposes, roof portion 40B may be latched closed with the latch mechanism 52A and 52B which is positioned inside the enclosure 1. Therefore, the roof portion 40B may be pivoted upward only after opening the latch mechanism from within the enclosure 1. Thus, only a person with a key to the lock on the door to the enclosure 1 may gain access to the enclosure 1 through roof 40. Any suitable latching mechanism 52 having the capability of maintaining the roof 40 in a closed position may be used. A preferred latch, Drawer-Tite Action Catch, Model # M10-8333, available from Component Hardware Co., 1890 Swarthmore Avenue, Lakewood, N.J., 08701, has been found to be a useful device for latching the roof 40 to the enclosure 1.

[0065] If ambient conditions are such that freezing may occur, then power may be delivered to the area enclosed by the enclosure 1 to maintain the temperature above a setpoint controlled by a controller, such as a thermostat. Power may be delivered via electrical current (alternating or direct), solar power, geothermal power, wind power and the like. For example, FIGS. 14 and 15 generally demonstrate mechanisms to maintain the temperature within the enclosure 1 above the freezing point of the fluid being conveyed through the piping P and the fluid conveying device FCD. Enclosure I may be placed upon slab 19 which may be fabricated at the surface or ground level S above gravel G. Gravel G may be replaced by heat transfer media having an enhanced heat storage capability to establish a heat sink having a greater thermal efficiency. For example, refractory materials may be employed such as magnesite brick, which has a specific heat of 0.27 Btu/lb/degree F and a density of 170 lb/cu. ft. resulting in a heat capacity that is approximately 50% greater than that of concrete. Other heat storage media, for example those having change of phase characteristics, such as media that release energy based on the heat of fusion, heat of sublimation, heat of vaporization or other latent heat releases are contemplated as useful sources of heat to maintain the temperature in the enclosure of this invention. The frost line F is also shown in FIG. 15.

[0066] In FIG. 14 the source of heat is radiant heater 35 which may be held in place by holder 34 to direct infared radiation toward the slab 19. Radiant heater 35 may be mounted anywhere on the interior walls or roof of the enclosure 1, the fluid conveying device FCD or piping P but should not be placed in contact with the slab 19. Radiant absorptivity is a measure of the total absorptive power of a real surface to that of a black body surface at the same temperature where the black body is 1.0. The radiant absorptivity of concrete and iron is about 0.9 compared to about 0.04 for aluminum. Thus, if the slab 19 is made of concrete and the fluid conveying device FCD is made of iron, a majority of the radiation will be absorbed into the slab and fluid conveying device. The small amount of radiation that is reflected from slab and fluid conveying device will be reflected back toward the slab 19 and fluid conveying device FCD from reflected surface 33, which is advantageously a reflective material such as aluminum foil. The air within the enclosure 1 becomes heated by convection from heated slab 19 and fluid conveying device FCD. Since warmer air rises, lower placement of the heating mechanism provides less thermal stratification and thus greater energy efficiency. A built-in thermostat 31 may be used to control radiant heater 35. An optional thermostat 32 may be utilized as a temperature sensing device to provide further or alternative control of heater 35. The reflective surface 33 is designed to cover the inside surfaces of the enclosure 1 and may be employed to direct radiant heat toward the fluid conveying device FCD and slab 19. Because the radiant heater 35 is held above the slab 19, it is out of the fluid discharge and drip zone of the fluid conveying device(s), thus it is easier to maintain. If the thermostat 31 is mounted to the radiant heater 35, then only a single run of conduit and wire need be employed to power the heating mechanism.

[0067] An alternative heating mechanism is depicted in FIG. 15. Before slab 19 is installed, a heater sleeve 29 may be oriented adjacent piping P. The heater sleeve 29 may extend below the position that slab 19 will eventually occupy and may further extend into gravel G or even below gravel G. Although not shown, heater sleeve 29 may extend into a naturally occurring or man-made void disposed below slab 19. Moreover, heater sleeve 29 may extend to a location which is equal to or below the frost line F. Heater sleeve 29 may be a conventional pipe or any other structural suitable for conducting heat and encasing a heater. At the top of heater sleeve 29 a housing 28 may be installed. Housing 28 is preferably liquid tight so that heater 30, which may be installed within heater sleeve 29, is protected from fluid which may leak or be discharged from fluid conveying device FCD. As stated above, gravel G may be replaced with a void or materials having a high heat storage capacity. As in FIG. 14, thermostats 31 and 32 and reflective surface 33 may be included in the apparatus depicted in FIG. 15.

[0068] Any suitable water-tight heater having the capability of maintaining the fluid conveying device and the material therein at a temperature high enough to avoid freezing the material the fluid conveying device may be used. A preferred radiant heater 35, liquid tight heater U-RAD-3LT, manufactured by Chromalox, 641 Alpha Drive, Pittsburgh, Pa., 15238, has been found to be a useful device for maintaining the temperature within the enclosure 1 in the embodiment illustrated in FIG. 14. A preferred heater 30, liquid tight heater type MTO-LT also manufactured by Chromalox has been found to be a useful heater in the embodiment depicted in FIG. 15. While any number of thermostats may be employed according to the principles of this invention, cartridge & hex head immersion Type 17000 and coupling head immersion type 18000, also manufactured by Chromalox, have been found to be useful thermal monitoring devices.

[0069] FIGS. 16, 17,17A, 17B, 18 and 19 illustrate other embodiments of the invention. FIG. 16 is a perspective view of an enclosure 1, including a door 6, that may be lifted as shown by arrow A and placed over a fluid conveying device and piping P. Although the functions are the same, enclosure 1 illustrated in FIG. 16 is a unitary structure which is distinct from the enclosure 1 shown in FIG. 1A which is made from a plurality of panels. A mounting bracket 22 is shown that may rest upon the upper surface of slab 19 or any other suitable surface. In this embodiment mounting bracket 22 is attached to slab 19 through the use of concrete fasteners (not shown) inserted through concrete fastening holes 27. After the mounting bracket 22 is fixed in place and the enclosure 1 is set on the mounting bracket 22, locking rod 24 may be employed then to hold enclosure 1 in place. Locking rod 24 may be inserted through hole 26 in riser portion 25, next through hole 2 in enclosure 1, next over trough 23, next through hole 2 in enclosure 1 (not shown), and finally through hole 26 in riser portion 25. Locking rod 24 may be made of stainless steel and may have a beveled end to facilitate the ease of sliding the locking rod 24 through the plurality of holes required to mount enclosure 1 to slab 19. A hole 24 h may be placed adjacent the end of the locking rod 24 in which a suitably sized padlock may be employed that cannot be pulled through hole 26 in riser portion 25. This provides security for the fluid conveying devices within the enclosure 1.

[0070]FIGS. 17, 17A and 18 display enclosure 1 with the upper portion of its panels and roof cut off. FIGS. 17 and 17A illustrate the fixed engagement of the mounting bracket 22 with the slab 19 and the releasably engageable relationship between enclosure 1 and mounting bracket 22. Because riser portions 25 are positioned outside of the exterior of enclosure 1 the alignment of holes 2 with holes 26 can be easily accomplished prior to insertion of the locking rod 24. Enlarged views of mounting bracket 22 are shown in FIGS. 17B and 19. FIG. 19 demonstrates one manner in which trough 23 may be fixed to the base 21 of the mounting bracket 22.

[0071] The method of installing mounting bracket 22 to slab 19 is as follows. First, mounting bracket 22 is centered between the inlet piping P and outlet piping P. Then the enclosure 1 is set over the fluid conveying device and into the mounting bracket 22 to ensure correct alignment and clearance around the fluid conveying device. The locking rod 24 is then inserted through holes 2 and holes 26 in the enclosure 1 and mounting bracket 22, respectively. Concrete fasteners are installed in the slab 19 by insertion through concrete fastening holes 27. Now that the mounting bracket is secured to the slab 19, the enclosure 1 may be lifted off and replaced as necessary.

[0072]FIG. 20 illustrates one embodiment of the invention. The elevated cover 101, along with structural pedestal chases 122, 123, enclose the backflow prevention device, which is shown in FIG. 20 as two check valves C, a relief valve R, servicing valves V and piping P. Although the invention is described for use in connection with a backflow prevention device, the enclosure may be employed to maintain the temperature of material being conveyed through any number of fluid conveying or monitoring devices, such as meters, vacuum breakers, standpipes, pressure regulators, and pumps (referred to generally as “fluid conveying devices”).

[0073] The assembly shown in FIG. 20 constitutes a portion of a substantially longer pipeline wherein a majority of the pipeline is installed underground. The backflow prevention device is constructed above the ground to allow for its monitoring and servicing. Additionally, if the device is one that discharges water, the backflow prevention device must be disposed high enough above ground level to permit the discharge of water to the atmosphere without submerging the backflow prevention device.

[0074] In this embodiment elevated cover 101 is depicted as a rectangular box that may be supported by structural pedestal chases 122, 123. Heater elements 124, 125 contained within elevated cover 101 and chases 122, 123 are utilized to maintain the backflow prevention device and associated valves and piping above the freezing point of the material transferred within the pipeline. The invention is particularly useful for pipelines carrying water, however its principles may be used for the protection of fluid conveying devices transferring any other material where either the material itself or the fluid conveying device surrounding the material is susceptible to solidification, such as a pressure regulator controlling the flow of natural gas. If the fluid conveying device has only one vertically rising pipeline or if one or more of the vertically rising pipelines are close together, then a single chase may be utilized to surround the piping and to support the elevated cover 101. On the other hand, if more than two chases are needed to cover a plurality of vertically disposed pipelines, such as when two or more backflow devices are constructed in parallel, then a number of chases may be employed to support an enlarged, elevated cover 101 and to surround the pipelines.

[0075] As shown in FIGS. 20 and 21, structural pedestal chases 122, 123 may extend below the surface S, which may be the ground, pavement, concrete, or the like, and may extend all the way to the frost line F. The temperature of the material and fluid conveying devices may be maintained to the frost line F by employing heater elements 124, 125 in the cover 101 and in the chases 122, 123. In warmer climates, however, the chases 122, 123 may be supported at ground level, e.g., on a concrete slab. The figures display concrete footers 127, 128 that may provide support for the piping P and the chases 122, 123. The bottom of these footers may be at or below the frost line F. Chases 122, 123 may be bolted to their supporting structures or attached in any suitable manner known in the art.

[0076]FIGS. 21 and 22 show greater detail of the elevated cover 101. The elevated cover 101 is illustrated as being defined by top wall 117, bottom wall 126, end doors 118, 119, stationary side walls 113-116, and access doors 111, 112. The wall and door material may be metal, wood, plastic or any other suitable material which is rigid enough to maintain its shape without collapsing due the effects of weather, UV radiation, vandalism, animals, discharge of high pressure water, and the like. In a preferred embodiment the walls and doors are made of insulation that is approximately 1½ inches thick covered with aluminum sheet metal that is about 0.050 to about 0.063 inches thick. The insulation may be polyisocyanurate or any other suitable insulating material that has a high R-value, such as an R-value of approximately 8. Of course, depending on weather conditions, fluid conveying factors, and other considerations, the construction and thicknesses of the walls and doors may vary.

[0077] The access doors 111, 112 may be attached to stationary side walls 113-116 at part lines 110 via any suitable, releasably engageable device. For example, access door 111 may be hinged to stationary side wall 113 at part line 110 a and may be releasably engaged to stationary side wall 114 at part line 110 b, or the entire access door 111 may be removable, to allow for service and monitoring of the backflow prevention device and the discharge valve 141 which may be installed below discharge port 140. Locking mechanisms (not shown) may be installed to discourage tampering or vandalism of the enclosed, fluid conveying devices. The construction of elevated cover 101 and the readily easy assembly and disassembly of its components is similar to that described in U.S. Pat. No. 4,890,638, the disclosure of which is incorporated by reference herein in its entirety. The enclosures utilized for smaller fluid conveying devices may be constructed as a unitary cover to avoid the complexities associated with the assembly and disassembly of cover components. The unitary cover consists of a top wall and side walls that may be lifted off of the bottom wall to allow access to the interior of the elevated cover 101.

[0078] If ambient conditions are such that freezing may occur, then power may be delivered to the area enclosed by the elevated cover 101 to maintain the temperature above a setpoint controlled by a controller, such as a thermostat. Power may be delivered via electrical current (alternating or direct), solar power, geothermal power, wind power, and the like. The power generator(s) may be located inside or outside of the elevated cover 101. For example, one or more heater elements 124, 125 may be installed within the elevated cover to control the temperature within the elevated cover 101. These heater elements 124, 125 may be disposed in a variety of places including the top, sides and bottom of the elevated cover 101 and the space between the piping P and the inside of one or more of the structural pedestal chases 122, 123. Any suitable heater having the capability of maintaining the fluid conveying device and the material therein at a temperature high enough to avoid freezing the material and the fluid conveying device may be used in combination with the elevated cover 101. A preferred heater, Formed Watrod, Catalogue #RGNA 132105, manufactured by Watlow, #6 Industrial Loop Road, Hannibal, Mo., has been found to be a useful device for maintaining the temperature within the elevated cover 101. In an alternative embodiment a heated fluid may be blown from outside the elevated cover 101 into the interior of the cover. The heated fluid may be generated by any suitable manner and from any source which heats the inside the cover, such as moving the fluid past an electric or gas heating element and directing it into the cover.

[0079] Elevated cover 101 may also enclose one or more electrical cabinets 120, 121, which may provide a junction box to heater elements 124, 125. In a preferred embodiment these cabinets 120, 121 are protected by the cover 101 as they are illustrated as being disposed in the end portions of the elevated cover 101 and are accessible via end doors 118, 119. FIG. 21A illustrates a preferred connection which may be employed to seal electrical cabinet 121 from any water discharged within the cover 101. Bulkhead gasket 142 a, bulkhead washer 142 b, and bulkhead nut 142 c may be utilized to fix heater element 125 and a junction box including an electrical box 143, electrical box extension 144, and flat cover plate 145 to inner electrical cabinet wall 121 a. Cabinets 120, 121 also may be installed just inside access doors 111, 112, along the side walls 113-116, near the top wall 117, or in a location outside of the elevated cover 101.

[0080]FIG. 23 is a view, partially in cross-section, of the elevated cover 101 along line 23-23 of FIG. 21. FIG. 23 illustrates the top wall 117, bottom wall 126, side walls 114 and 116, and the end door 119 of the elevated cover 101. Structural pedestal chase 123 is shown extending through the surface S and continuing all the way down through the concrete footer 128 to the frost line F. This view illustrates heater element 125, in phantom, extending from the elevated cover 101 and along the chase 123 to the frost line F. Due to the excessive stratification of heat within a cover of the type described by the invention, a lower location of the heater element assures the maintenance of the temperature of the material and the portion of the piping P that is below the ground surface S yet above the frost line F.

[0081]FIG. 23A is an enlargement of FIG. 23 and illustrates one manner in which the top wall 117 and side wall 114 may be joined. The top wall 117 is additionally supported by roof structural member 146. FIGS. 24 and 25 generally demonstrate a preferred structural method of supporting elevated cover 101 upon structural support zees 147, 148 which are supported upon chases 122, 123. More specifically, FIG. 24 shows access door 111 resting upon structural support zee 148. Although not illustrated, side walls 113-116 may be supported upon zees 147, 148. Zees 147, 148 may be fabricated by bending lengths of sheet metal.

[0082] FIGS. 26-30 provide an illustration of one discharge valve constructed according to the principles of the invention. FIG. 26 shows a side elevational view of discharge valve 141. Discharge valve 141 is located far enough below bottom wall 126 and has an opening that is large enough so that discharged water does not accumulate in elevated cover 101. Discharge valve 141 is illustrated as being formed of two valve halves 131, 132 that are secured to the bottom wall 126 of the elevated cover 101. As shown in FIG. 27, valve halve 131 (and valve halve 132, not shown) may also be secured at valve halve ends 138, 139 to structural frame members 136, 137. When the backflow prevention device dumps a large volume of water, and even when it drips smaller quantities, discharge valve 141 will open and allow water stream W to be removed from the elevated cover 101.

[0083] The operation of discharge valve 141 is described in connection with FIGS. 28-30. FIG. 28 illustrates discharge valve 141 in the closed position and FIG. 30 demonstrates a fully open discharge valve 141. FIGS. 29A and 29B are intermediate and show discharge valve 141 in partially opened positions. For the purposes of this discussion the four corners of valve halve 132 have been identified as corners A, B, C and D. As described above, corner D may be attached to bottom wall 126 and to structural frame members 136, 137 at its ends 138, 139 and thus remains in the same location regardless of the position of valve halve 132. Depending on the strength and flexibility of the material of construction of discharge valve 141, corner C may rotate away from the flow of water or may remain in substantially the same position during the opening and closing of discharge valve 141. For the purposes of this discussion, corner C will essentially remain in the same location during operation of discharge valve 141.

[0084]FIG. 28 shows the discharge valve 141 as it is depicted in FIG. 26. As water flows toward discharge valve 141, corners A and B are deflected downward and valve halves 131 and 132 are separated, thereby allowing water to be transferred from the lower portion of elevated cover 101. This partially opened position is illustrated in FIGS. 29A and 29B. Depending on the strength and flexibility of the material of construction of the discharge valve 141, the segment of the valve halve 132 between corner D and corner A may (FIG. 29B) or may not (FIG. 29A) deflect. In the fully open position as illustrated in FIG. 30, corners A and B are further deflected downward and the segment of the valve halve 132 between corner C and corner B is shown in a flexed position. The valve halves 131 and 132 return to their original position, as is shown in FIGS. 26 and 28, after the backflow prevention device completes discharging and the water flowing toward discharge valve 141 is removed.

[0085]FIGS. 31 and 32 illustrate another discharge valve 141′ that is useful in combination with the elevated cover of the invention. FIG. 31 shows a side elevational view of discharge valve 141′. Discharge valve 141′ may be formed through the combination of a diverter shield 133 and a pair of valve flaps 129, 130. Although FIG. 31 illustrates the use of two valve flaps, this embodiment of the invention contemplates the use of a single flap or more than two flaps if warranted by the installation conditions, such as water throughput, discharge pressure of the pipeline, size of the cover, and the like. The diverter shield 133 may be insulated to minimize the loss of heat therethrough. In a preferred embodiment illustrated in FIG. 31A, diverter shield 133 may be formed as a tent-like structure having a pair of ascending walls 133 a forming an inverted Vee, a pair of side walls 133 b attached to the ascending walls 133 a, and a bottom wall 133 c. This structure may be insulated by injecting liquid insulation into a hole 133 d formed in wall 133 a and then sealing hole 133 d.

[0086] In the embodiment illustrated in FIGS. 31 and 32, the diverter shield 133 may be supported by structural frame members 136, 137, however any suitable device supporting the diverter shield 133 in a position to form discharge valve 141′ is contemplated by the invention. Valve flaps 129, 130 are secured to the bottom wall 126 of elevated cover 101 and extend to and lay over diverter shield 133. The amount of surface contact between valve flaps 129, 130 and diverter shield 133 may be large or may be minimal as is shown in FIG. 31.

[0087] As shown in FIG. 32, valve flap 129 (and valve flap 130, not shown) may also be secured at valve flap ends 138, 139 to structural frame members 136, 137. Like discharge valve 141, discharge valve 141′ may be disposed far enough below bottom wall 126 and has a large enough opening that discharged water does not accumulate within cover 101. When the backflow prevention device discharges any volume of material, water stream W will force valve flaps 129, 130 away from diverter shield 133 and allow the discharged water to be removed from elevated cover 101. As the water flows out of the elevated cover 101 the valve flaps 129′, 130′ will be forced upwardly and outwardly away from diverter shield 133, as is shown in FIG. 31. Of course, the flexing of the valve flaps 129, 130 will depend on the strength and flexibility of the material of construction of the valve flaps 129, 130.

[0088] Any material that flexes enough so that it forms an opening and is resilient enough to return to its original position and seal the discharge opening is a material that may be successfully utilized as the material of construction for the valve flaps 129, 130 and valve halves 131, 132. Cured reinforced or non-reinforced EPDM (Terpolymer of Ethylene, Propylene, and Diene) compounded elastomer available as “Sure-Seal EPDM membrane” from Carlisle Tire & Rubber, Carlisle, Pa., is a preferred material due to its flexibility, strength and resiliency over a wide range of temperatures. In a preferred embodiment the material utilized for valve flaps 129, 130 may be produced from extruded sheet material having a thickness of approximately 0.06 inches. The material used for valve halves 131, 132 may be manufactured via extrusion through a die which provides for the hollow shape illustrated in FIG. 24.

[0089] It is believed that the structural arrangement of the cover 101 and discharge valves 141, 141′ is such that accumulation of material and substantial flooding of the chases 122, 123 will be avoided or minimized. However, flooding of the space between piping P and the structural pedestal chases 122, 123 with water will not defeat the advantages of the elevated cover 101 since the water either will leak past the bottom of chases 122, 123, will evaporate due to ambient temperatures or, if the elevated cover includes heater elements 124, 125, will evaporate due to temperatures created by these heaters. Additionally, to avoid the problems associated with the discharge of water, the utilization of closed cell insulation, water proof adhesives, heating elements designed for immersion heating of liquids, and metals selected for their corrosion resistance are preferred. 

What is claimed is:
 1. Apparatus for protecting a fluid conveying device in fluid communication with valves and piping, comprising: a top and walls extending downward from the top, a self-closing, gravity-biased door, and insulation integrated into said top, said walls and said door.
 2. The apparatus of claim 1 wherein said door comprises a notched portion.
 3. The apparatus of claim 1 wherein the upper portion of the door is connected to the lower portion of one of said walls.
 4. The apparatus of claim 1 further comprising a pivot between said wall and said door and a door stop wherein said pivot and said stop are in the same vertical plane.
 5. The apparatus of claim 4 wherein said pivot is a hinge.
 6. The apparatus of claim 4 wherein said stop comprises a zee.
 7. The apparatus of claim 1 further comprising a water-proof heater placed in the lower portion of the apparatus.
 8. Apparatus for protecting a fluid conveying device in fluid communication with valves and piping, comprising: a top and walls extending downward from the top forming an enclosure having a length and width, wherein the length is greater than the width of the enclosure, and a mounting bracket, said mounting bracket having at least two riser portions, wherein the distance between the riser portions is greater than the width of said enclosure.
 9. The apparatus of claim 8 further comprising a rod, and wherein said enclosure and said mounting bracket contain openings, said openings being aligned when the enclosure is resting upon the mounting bracket and permitting insertion of said rod therethrough.
 10. The apparatus of claim 9 further comprising a lock, and wherein said rod comprises a handle at one end and an opening at the other end, and further wherein said lock is inserted through the opening in said rod to prevent said enclosure from being removed from said mounting bracket.
 11. The apparatus of claim 8 wherein said mounting bracket further comprises mounting holes.
 12. The apparatus of claim 8 wherein said mounting bracket further comprises a trough.
 13. Apparatus for protecting a fluid conveying device in fluid communication with valves and piping, comprising: a top and walls extending downward from the top, said top formed of a plurality of top portions, and a hinge connecting the top portions.
 14. The apparatus of claim 13 further comprising a latch to secure at least one of the plurality of top portions, said latch being accessible only through the interior of the enclosure.
 15. The apparatus of claim 13 further comprising an alignment guide to establish the opening for a center panel and to aide in the assembly of said apparatus.
 16. The apparatus of claim 13 further comprising tabs extending from the lower portions of said walls, said tabs being integral with said walls.
 17. Apparatus for protecting a fluid conveying device in fluid communication with valves and piping, said apparatus adapted to rest upon a slab, comprising: a top and walls extending downward from the top, a radiant heater, a holder for said radiant heater, and a thermostat to control said radiant heater, wherein the output of said radiant heater is directed toward the slab.
 18. The apparatus of claim 17 further comprising insulation covering said top and walls.
 19. The apparatus of claim 17 further comprising a reflective surface covering said top and walls.
 20. Apparatus for protecting a fluid conveying device in fluid communication with valves and piping, said apparatus adapted to rest upon a slab, comprising: a top and walls extending downward from the top, and a sleeve extending into the slab.
 21. The apparatus of claim 20 wherein said sleeve extends below the lower portion of the slab.
 22. The apparatus of claim 20 wherein said sleeve extends to the frost line.
 23. The apparatus of claim 20 further comprising a heater, said heater being placed within said sleeve.
 24. The apparatus of claim 21 further comprising an open space below the slab.
 25. The apparatus of claim 21 further comprising heat transfer media disposed below the slab. 